fix declaration of PyBuffer_FillInfo()

Cython/Includes/cpython/buffer.pxd

@@ -96,9 +96,8 @@ cdef extern from "Python.h":
     # (Fortran-style if fort is 'F' or C-style otherwise) array of the
     # given shape with the given number of bytes per element.
 
-    int PyBuffer_FillInfo(Py_buffer *view, void *buf,
-                          Py_ssize_t len, int readonly,
-                          int flags) except -1
+    int PyBuffer_FillInfo(Py_buffer *view, object exporter, void *buf,
+                          Py_ssize_t len, int readonly, int flags) except -1
     # Fill in a buffer-info structure, view, correctly for an exporter
     # that can only share a contiguous chunk of memory of “unsigned
     # bytes” of the given length. Return 0 on success and -1 (with